Variable imaging arrangements and methods therefor

Abstract

Various approaches to imaging involve selecting directional and spatial resolution. According to an example embodiment, images are computed using an imaging arrangement to facilitate selective directional and spatial aspects of the detection and processing of light data. Light passed through a main lens is directed to photosensors via a plurality of microlenses. The separation between the microlenses and photosensors is set to facilitate directional and/or spatial resolution in recorded light data, and facilitating refocusing power and/or image resolution in images computed from the recorded light data. In one implementation, the separation is varied between zero and one focal length of the microlenses to respectively facilitate spatial and directional resolution (with increasing directional resolution, hence refocusing power, as the separation approaches one focal length).

1. A digital imaging system comprising:
 an optics arrangement, including a main lens, and a microlens array at a two dimensional focal plane of the main lens; 
 a photosensor array comprising a plurality of photosensors, wherein the optic arrangement directs light rays from a scene to be sensed by the photosensor array, and wherein the photosensor array outputs light data characterizing the sensed light rays; and 
 a control arrangement configurable to set a distance between the photosensor array and the microlens array, wherein at a first position the distance is approximately zero, and a spatial resolution of an image of the scene captured by the digital imaging system approaches a maximum achievable value, and wherein at a second position the distance is approximately one focal length of the microlens array, and the image of the scene captured by the imaging arrangement approaches a maximum achievable directional resolution such that a focal point of the captured image may be changed after the image of the scene is captured. 
 
     
     
       2. The system of  claim 1 , wherein the control arrangement is further configurable to set the distance to be any distance between the distance of the first position and the distance of the second position, and wherein distances closer to the distance of the first position result in captured images with relatively greater spatial resolution, relatively less directional resolution and more defocusing of images formed by individual microlenses, while distances closer to the distance of the second position result in captured images with relatively greater directional resolution, relatively less spatial resolution, and more defocusing of the image formed by the optics arrangement. 
     
     
       3. The system of  claim 1 , wherein the control arrangement includes an actuator and a controller. 
     
     
       4. The system of  claim 1 , wherein the control arrangement moves the photosensor array to set the relative distance between the photosensor array and the microlens array. 
     
     
       5. The system of  claim 1 , wherein the control arrangement moves the microlens array to set the relative distance between the photosensor array and the microlens array. 
     
     
       6. The digital imaging system of  claim 1 , further comprising a processor programmed to generate image data characterizing a synthesized image of the scene as a function of the sensed light rays at different photosensors during image capture, the position of the photosensors relative to the microlens array, and an angle of incidence of the sensed light rays upon the two-dimensional focal plane, wherein the processor is further programmed to operate on the image data to generate an output image of the scene in which at least a portion of the image of the scene is refocused to have a focal point that is not on the two-dimensional focal plane. 
     
     
       7. The system of  claim 6 , wherein generating image data characterizing the synthesized image of the scene comprises determining for light rays sensed at each photosensor an expression L(x, u) where u is a position on the main lens through which a ray passes, and x is a photosensor location. 
     
     
       8. The system of  claim 6 , further including an auto-focus sensor to detect a depth of a subject in the scene being captured, wherein the control arrangement positions the photosensor array relative to the microlens array as a function of the depth of the subject, and wherein the processor is programmed to operate on the image data to generate an output image that is focused on the depth of the subject. 
     
     
       9. The system of  claim 6 , wherein generating the output image of the scene comprises anti-aliasing the output image, including combining light ray samples from multiple spatial locations. 
     
     
       10. The system of  claim 9 , wherein the control arrangement positions the photosensor array relative to the microlens array at a non-zero mis-focus position of the photosensor array when the light from the scene is sensed by the photosensor array, and wherein light ray samples combined are from multiple spatial locations at the mis-focus position of the photosensor array. 
     
     
       11. The system of  claim 10 , wherein combining light ray samples comprises computationally resampling the light rays as a function of a ray-tracing approach for determining where the light rays passing into the system terminate on the photosensor array. 
     
     
       12. The system of  claim 1 , wherein, the distance between the photosensor array and the microlens array is related to selective detection of directional characteristics of the light ray data recorded by the photosensor array corresponding to a selectable trade-off between degrees of spatial resolution and directional resolution in the generated output image. 
     
     
       13. A digital imaging system comprising:
 a main lens; 
 a photosensor array configured to collect a set of light rays via the main lens during the capture of an image, and to output light data characterizing the set of light rays and corresponding to the captured image; 
 a microlens array, between the main lens and the photosensor array, the microlens array configurable to form a plurality of images on the photosensor array, each of the plurality of images corresponding to an individual microlens and including directional characteristics of light rays passing through the individual microlens; and 
 a positioning arrangement configurable to set a distance of the plane of the photosensor array relative to the plane of the microlens array, wherein a minimum distance corresponds to a maximum focus of an image formed by the main lens and a minimum focus of the plurality of images formed by the microlens array, while a maximum distance corresponds to a minimum focus of an image formed by the main lens and a maximum focus of the plurality of images formed by the microlens array. 
 
     
     
       14. The system of  claim 13 , wherein the minimum distance is about zero and the maximum distance is about equal to one focal length of a microlens in the microlens array. 
     
     
       15. The system of  claim 13 , wherein the minimum distance is-about zero and the maximum distance is greater than one focal length of a microlens in the microlens array. 
     
     
       16. The digital imaging system of  claim 13 , further comprising an image data processor to compute synthesized image data using the light data from the image capture, wherein the synthesized image data is computed as a function of the set distance. 
     
     
       17. An imaging method, comprising:
 collecting image data, wherein collecting comprises,
 setting a selectable distance between a photosensor array and a microlens array in an imaging device, wherein the photosensor array and the microlens array are on an opposite side of a main lens from a scene to be captured by the imaging device, wherein at a minimum selectable distance the image data has optimum spatial resolution, and as the selectable distance increases, the spatial resolution of the image data decreases while directional resolution of the image data increases; and 
 collecting light field data during a scene capture using the imaging device, the light field data comprising a plurality of light rays originating from the scene, wherein, for light rays passing through a particular portion of a two dimensional focal plane, a plurality of photosensors in the photosensor array are arranged to sense different ones of the light rays that concurrently arrive at the particular portion of the two-dimensional focal plane at different angles of incidence, and to output light field data characterizing the sensed light rays. 
 
 
     
     
       18. The method of  claim 17 , further comprising:
 receiving the light field data in a processing circuit; and 
 processing the light field data for generating a synthesized image of the scene, wherein processing comprises changing a focus of the synthesized image from the focal point of the two-dimensional focal plane when the image data has sufficient directional resolution as determined by the selectable distance. 
 
     
     
       19. The method of  claim 17 , further comprising:
 receiving the light field data in a processing circuit; and 
 processing the light field data for generating a synthesized image of the scene that is focused at the focal point of the two-dimensional plane. 
 
     
     
       20. The method of  claim 17 , wherein processing the light field data further comprises determining, for light rays sensed at each photosensor, an expression L(x, u) where u is a position on the main lens through which a light ray passes, and x is a photosensor location. 
     
     
       21. The method of  claim 17 , wherein processing the light field data further comprises anti-aliasing the output image, including combining light ray samples from multiple spatial locations. 
     
     
       22. The method of  claim 21 , further comprising setting the selectable distance to position the photosensor array relative to the microlens array at a non-zero mis-focus position of the photosensor array when the light rays from the scene are sensed by the photosensor array, and wherein the light ray samples combined are from multiple spatial locations at the mis-focus position of the photosensor. 
     
     
       23. The method of  claim 22 , wherein combining light ray samples comprises computationally resampling the light rays as a function of a ray-tracing approach for determining where the light rays passing into the imaging device terminate on the photosensor array. 
     
     
       24. The method of  claim 17 , wherein, setting the selectable distance between the photosensor array and the microlens array facilitates selective detection of directional characteristics of the light rays data recorded by the photosensor array corresponding to a selectable trade-off between degrees of spatial resolution and directional resolution in the synthesized image.